Automatic air-compressor unit



Aug. 9, 1927,

- 1,638,212 J. RAYFIELD AUTOMATIC AIR CCSMPRESSOR UNIT Filed ADIil 30,1925 2 Sheets-Sheet l ill" #14 0 v2 {EEK Fred J R fzezd F. J. RAYFIELDAUTOMATIC AIR COMPRESSOR UNIT 2 Shoots-Sheet 2 Aug. 9, 127.

Filed April 30, 1925 I I i 26 E o w I I? 2 C v v E 1:!

.& 1

I Fred J: Rayfild Patented Aug. 9, 1927.

UNITED STATES 1,638,212 PATENT OFFICE.

FRED JZ' RAYFIELD, OF CHICAGO, ILLINOIS. ASSIGNOR, TO CHAMPION PNEUMATICMACHINERY 00., A CORPORATION OF ILLINOIS.

AUTOMATIC AIR-ooMrREsson' UNIT. i

Application filedApril 30, 1925. .Serial No. 26,855.

This invention relates to the automatic control of storage type aircompressors adapted to maintain the air pressure within .apredeterminedrange.

It is an object ofthis invention to provide an improved air compressorsystem which is fully automatic in operation 'although using a watercooled compressor. Heretofore automatically controlled air compressorunits have been limited to the smaller sizes due to the necessity of theuse of air cooled compressors because of difliculti es in the practicalcontrol of the cooling water system of the larger compressors. Thisinvention provides means for automatically controlling the watercirculation in step with the automatic control of the compressor proper,and includes in this control an unloading device for the compressor thatwill allow the starting thereof without initial loadeven though the mainair reservoir is under considerable pressure.

It is another object of this invention to provide a cooling watercontrol, for use in connection with an automatic air compressorsystem,:wherein the water control will be timed to'stop the water;circulation slightly after stoppageof. the air compressor and to startthe water circulation after-the air compressor starts again. 5, i

It is also an ob 'ect of this invention to provide a settling chamberintermediate the air compressor and'receiver and to provide meansventing thischamber upon stoppage of the compressor; the venting of thechamber serving to unload the compressor for restarting and to shut oflthe cooling water circulation for the compressor. when the pressure inthe chamber drops below a predetermined point. 7 7

It. is a further object Let this invention to provide an improved andsimplified fully automatic control for an air compressing system adaptedto be easily and economically manufactured, installed, and maintained.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and drawings.

The invention (in a preferred form) is illustrated in the drawings andhereinafter more fully described.

On the drawings:

Figure 1 is a side elevation of an automatic air compressing apparatusembodying thefeatures of this invention.

7 parts in section.

I Figure 2 is a top plan view thereof ona.

reduced scale.

Figure 3 is a-fragmentary diagrammatic elevation of the water and aircircuits with Figure 4 is'la vertical central section through theautomatic control.

Figure 5 is a section on the line 55 of Figure 4. i

Asshown on the drawings: The self containedand automatically .controlledair compressor outfit shown comprises a water jacketed air compressorhavinga belt drive 11 from a motor 12, an idler pulley 13 being providedto maintain proper belt tension. 7 The air compressor delivers air to asmall settling tank 14 through the-pipe 15 and thence to the main airreservoir 16 throughthe pipe 17 which contains a check valve 18. toprevent back flow. A

pipe 19 from the air reservoir connects to an automatlc electriccontroller 20 which controls the operation of the motor. The wholeapparatus mentioned is compactly mounted on a base 21 as .shown inFigure 2. sothat the ,outfitis a unit requiring only water and electricconnection from external sources.

The. specific form of automatic electric controller 20 per se does notenter into this invention except as an element of the generalcombination. It is, therefore, necessary only to briefly describe theconstruction and operation of the particular form chosen forillustration. This controller is provided with an operating lever 22pivoted. at '23. One'end of the lever is connected to and is adapted toopen and close a current controller switch 24, and. the other end isprovided with a V- shaped projection or cam 25 against which a roller 26in aspring. urged lever 27 is held. .Theroller 26 is adapted. to beraised and lowered by the air pressure in the reservoir 16 by means of adiaphragm comprising one wall of a pressure chamber 28 connected to thereservoir by the pipe 19. As the pressure in the main reservoirincreases the roller travels up the lower incline of the cam 25 until itpasses the peak thereof, at which time the spring pressure to which thelever 27 is subjected causes the roller to advance on the upper inclineof'the cam thus depressing the cam end of the lever 22. By this meansthe circuit supplying current to the motor is broken and the compressorstops.

As the pressure decreases in the reservoir the roller descends theupper-incline until it passes the peak of the cam and then it acts tolift the end of the lever 22 and close the circuit to start the motor. Aspring 29 is provided which is adjustable to control the pressure in thereservoir. This switch mechanism is a snap-over switch in that it issuddenly opened and closed as the roller passes over the peak of the cam25.

A bleeder pipe 30 is connected between the pipe 17 below the check valveand a vent valve 31 operated by the motor controller 20. This bleederpipe serves to relieve the pressure within the settling chamber and totherefore unload the compressor upon stoppage thereof so that restartingwill be without appreciable initial load. Such a mode of operation isparticularly necessary with A.

G. motors because of the difliculty of starting such motors under load.Thevent valve 31 comprises a housing 32 secured to the side of thecontroller housing'andprovided with an inlet- 83 connected to thebleeder pipe and-an outlet 84. Between the inlet and outlet is avertical passage having a normally closed ball valve 35 therein. To openthe vent when the motor stops a plunger rod 36 is mounted verticall inthe casin C and adapted to be depressed to force the ball off its seat.To accomplish this the rod 36 is positionedtobe engaged by a pin 37projecting from' the lever 22 near the cam 25. This pin engages the rod36 when the lever 22 is depressed to open the motor circuit.

The water supply for the cooling jacket of the compressor is broughtthereto by the pipe 38 and discharges therefrom through the pipe 39having a control valve 40 mounted therein. The valve 40 comprises aspring loaded disc 41 normally'closing the outlet passage, and analigned piston 42 and plunger 48 adapted to force the disc 41 off itsseat when air pressure is conducted behind the piston by the pipe 44leading to the settling tank.

The operation of this air compressor outfit has been partly described inconnection with the automatic controller whereby shutting down the motorreleases the pressure within the small settling chamber. The completerelease of pressure is somewhat delayed due to' the small size of thebleeder pipe and therefore the water valve will have a lag with respectto the action of the controller, the valve 40 not closing to stop thewater circulation until the pressure drops considerably. The continuedwater circulation prevents overheating due to the heat stored up in thecylinders and pistons of the compressor which in the case ofsimultaneous stoppage of both the compressor and water circulation mightcause overheating of the water tapped in the water jackets. Similarlythevalve' 40 is not opened upon starting the motor until the pressure inthesettling tank is built up again so that the compessor has a chance towarm up its jacket water and to approximate a favorable temperature forlubrication and piston sealing before the water circulation startsagain. This'control of the water circulation in accordance with theoperation of the compressor brings the'larger sizes of compressors,necessarily water cooled, within the bounds of. full automatic control,andthe slight lag in the water :con-

trol approximates this feature of manual control automatically. V

I am aware that numerous details of construction may be varied through awide range without departing from the principles of in said settlingchamber and means respon-- sive to the pressure in said settling chamberadapted to shut off the cooling Water circu-- lation for said compressorafter the release of the pressure in said settling chamber.

In testimony whereof I have hereunto subscribed by name.

FRED J. RAYFI'ELD.

